Acid soil indicators in forest soils of the Cherry River Watershed, West Virginia

Declining forest health has been observed during the past several decades in several areas of the eastern USA, and some of this decline is attributed to acid deposition. Decreases in soil pH and increases in soil acidity are indicators of potential impacts on tree growth due to acid inputs and Al toxicity. The Cherry River watershed, which lies within the Monongahela National Forest in West Virginia, has some of the highest rates of acid deposition in Appalachia. East and West areas within the watershed, which showed differences in precipitation, stream chemistry, and vegetation composition, were compared to evaluate soil acidity conditions and to assess their degree of risk on tree growth. Thirty-one soil pits in the West area and 36 pits in the East area were dug and described, and soil samples from each horizon were analyzed for chemical parameters. In A horizons, East area soils averaged 3.7 pH with 9.4 cmol_c kg^???1 of acidity compared to pH 4.0 and 6.2 cmol_c kg^???1 of acidity in West area soils. Extractable cations (Ca, Mg, and Al) were significantly higher in the A, transition, and upper B horizons of East versus West soils. However, even with differences in cation concentrations, Ca/Al molar ratios were similar for East and West soils. For both sites using the Ca/Al ratio, a 50% risk of impaired tree growth was found for A horizons, while a 75% risk was found for deeper horizons. Low concentrations of base cations and high extractable Al in these soils translate into a high degree of risk for forest regeneration and tree growth after conventional tree harvesting.     

Water quality changes in a polluted stream over a twenty-five-year period

The Deckers Creek watershed in northern West Virginia (USA), containing a land area of 166 km2 (63 mi2), has a long history of industrial development and attendant environmental abuses from both land and water pollution practices. The water in Deckers Creek was sampled in 1974 at 29 locations along the main stem and resampled in 1999-2000 to determine water quality changes over this 25-year period. Water samples were analyzed for pH, acidity, alkalinity, iron, and calcium at both times, while aluminum, manganese, zinc, and fecal coliform (FC) bacteria densities were added in 1999-2000. Water at almost all sampling points showed lower acidity and metal contents in 1999-2000 compared with 1974. Water pH increased at the mouth from 5.4 in 1974 to 6.0 in 1999-2000. Acidity and iron concentrations were decreased an average of 70% in the upper stretches of the creek. However, one major untreated point source of water from an abandoned underground mining complex continues to degrade the quality of the creek in its lower stretches. In the upper section, the water quality in Deckers Creek has improved due to decreased surface and underground coal mining activities, reclamation of abandoned and recently permitted surface mined lands, and natural healing of past land use scars from timbering and mining over time. The decrease in mineral extraction activities and the reclamation of disturbed lands has occurred due to the passage and enforcement of water quality and land reclamation laws and regulations. More time and additional reclamation projects will continue to enhance the water quality in the creek. Improved water chemistry in the majority of the creek, however, shows the previously unnoticeable biological contamination from sewage inputs.     

Acid-base accounting to predict post-mining drainage quality on surface mines

Acid-base accounting (ABA) is an analytical procedure that provides values to help assess the acid-producing and acid-neutralizing potential of overburden rocks prior to coal mining and other large-scale excavations. This procedure was developed by West Virginia University scientists during the 1960s. After the passage of laws requiring an assessment of surface mining on water quality, ABA became a preferred method to predict post-mining water quality, and permitting decisions for surface mines are largely based on the values determined by ABA. To predict the post-mining water quality, the amount of acid-producing rock is compared with the amount of acid-neutralizing rock, and a prediction of the water quality at the site (whether acid or alkaline) is obtained. We gathered geologic and geographic data for 56 mined sites in West Virginia, which allowed us to estimate total overburden amounts, and values were determined for maximum potential acidity (MPA), neutralization potential (NP), net neutralization potential (NNP), and NP to MPA ratios for each site based on ABA. These values were correlated to post-mining water quality from springs or seeps on the mined property. Overburden mass was determined by three methods, with the method used by Pennsylvania researchers showing the most accurate results for overburden mass. A poor relationship existed between MPA and post-mining water quality, NP was intermediate, and NNP and the NP to MPA ratio showed the best prediction accuracy. In this study, NNP and the NP to MPA ratio gave identical water quality prediction results. Therefore, with NP to MPA ratios, values were separated into categories: <1 should produce acid drainage, between 1 and 2 can produce either acid or alkaline water conditions, and >2 should produce alkaline water. On our 56 surface mined sites, NP to MPA ratios varied from 0.1 to 31, and six sites (11%) did not fit the expected pattern using this category approach. Two sites with ratios <1 did not produce acid drainage as predicted (the drainage was neutral), and four sites with a ratio >2 produced acid drainage when they should not have. These latter four sites were either mined very slowly, had nonrepresentative ABA data, received water from an adjacent underground mine, or had a surface mining practice that degraded the water. In general, an NP to MPA ratio of <1 produced mostly acid drainage sites, between 1 and 2 produced mostly alkaline drainage sites, while NP to MPA ratios >2 produced alkaline drainage with a few exceptions. Using these values, ABA is a good tool to assess overburden quality before surface mining and to predict post-mining drainage quality after mining. The interpretation from ABA values was correct in 50 out of 52 cases (96%), excluding the four anomalous sites, which had acid water for reasons other than overburden quality.     

Restoring Forests and Associated Ecosystem Services on Appalachian Coal Surface Mines

Surface coal mining in Appalachia has caused extensive replacement of forest with non-forested land cover, much of which is unmanaged and unproductive. Although forested ecosystems are valued by society for both marketable products and ecosystem services, forests have not been restored on most Appalachian mined lands because traditional reclamation practices, encouraged by regulatory policies, created conditions poorly suited for reforestation. Reclamation scientists have studied productive forests growing on older mine sites, established forest vegetation experimentally on recent mines, and identified mine reclamation practices that encourage forest vegetation re-establishment. Based on these findings, they developed a Forestry Reclamation Approach (FRA) that can be employed by coal mining firms to restore forest vegetation. Scientists and mine regulators, working collaboratively, have communicated the FRA to the coal industry and to regulatory enforcement personnel. Today, the FRA is used routinely by many coal mining firms, and thousands of mined hectares have been reclaimed to restore productive mine soils and planted with native forest trees. Reclamation of coal mines using the FRA is expected to restore these lands’ capabilities to provide forest-based ecosystem services, such as wood production, atmospheric carbon sequestration, wildlife habitat, watershed protection, and water quality protection to a greater extent than conventional reclamation practices.     

Ameliorants to immobilize Cd in rice paddy soils contaminated by abandoned metal mines in Korea

The cadmium (Cd) content of rice grain grown in metal-contaminated paddy soils near abandoned metal mines in South Korea was found to exceed safety guidelines (0.2 mg Cd kg?1) set by the Korea Food and Drug Administration (KFDA). However, current remediation technologies for heavy metal-contaminated soils have limited application with respect to rice paddy soils. Laboratory and greenhouse experiments were conducted to assess the effects of amending contaminated rice paddy soils with zerovalent iron (ZVI), lime, humus, compost, and combinations of these compounds to immobilize Cd and inhibit Cd translocation to rice grain. Sequential extraction analysis revealed that treatment with the ameliorants induced a 50-90% decrease in the bioavailable Cd fractions when compared to the untreated control soil. When compared to the control, Cd uptake by rice was decreased in response to treatment with ZVI + humus (69%), lime (65%), ZVI + compost (61%), compost (46%), ZVI (42%), and humus (14%). In addition, ameliorants did not influence rice yield when compared to that of the control. Overall, the results of this study indicated that remediation technologies using ameliorants effectively reduce Cd bioavailability and uptake in contaminated rice paddy soils.     

Ameliorants to immobilize Cd in rice paddy soils contaminated by abandoned metal mines in Korea

The Yarlung Tsangbo (YT) is a large river running across southern Tibet and has significant effects on its lower reaches, the Ganges–Brahmaputra Basin. In order to investigate the geochemical features of the YT, 18 surface sediment samples were collected; ten trace element concentrations were measured for bulk sediments and two fine grain size fractions. Meanwhile, basic physicochemical parameters and element concentrations of river water were also analyzed. Results indicated that the river water was alkaline (pH 8.42) and that dissolved oxygen was mainly controlled by river water temperature. Some elements (e.g., Zn and Ni) showed close negative relationship to mean grain size of the sediments. Concentrations of most heavy metals, except As of the YT bulk sediments, were similar to those of Upper Crustal Concentration and its lower reaches, indicating almost no anthropogenic impact. Arsenic of the YT sediments was derived fundamentally from the parent rocks of the YT Basin and was far higher than that of its lower reaches. This indicates that relatively small amounts of As from the study area were transported down to the Brahmaputra River under present, relatively dry climatic conditions. However, more YT sediments might have been transported to its low reaches during the Holocene due to the wet climate, giving high As concentration in Holocene sediments of the Ganges–Brahmaputra Basin. Thus, As transported by the YT may produce important influence on the Ganges–Brahmaputra Basin and contribute to its high As concentration in groundwater.     

Longevity of acid discharges from underground mines located above the regional water table

The duration of acid mine drainage flowing out of underground mines is important in the design of watershed restoration and abandoned mine land reclamation projects. Past studies have reported that acid water flows from underground mines for hundreds of years with little change, while others state that poor drainage quality may last only 20 to 40 years. More than 150 above-drainage (those not flooded after abandonment) underground mine discharges from Pittsburgh and Upper Freeport coal seams were located and sampled during 1968 in northern West Virginia, and we revisited 44 of those sites in 1999-2000 and measured water flow, pH, acidity, Fe, sulfate, and conductivity. We found no significant difference in flows between 1968 and 1999-2000. Therefore, we felt the water quality data could be compared and the data represented real changes in pollutant concentrations. There were significant water quality differences between year and coal seam, but no effect of disturbance. While pH was not significantly improved, average total acidity declined 79% between 1968 and 1999-2000 in Pittsburgh mines (from 66.8 to 14 mmol H+ L(-1)) and 56% in Upper Freeport mines (from 23.8 to 10.4 mmol H+ L(-1)). Iron decreased an average of about 80% across all sites (from an average of 400 to 72 mg L(-1)), while sulfate decreased between 50 and 75%. Pittsburgh seam discharge water was much worse in 1968 than Upper Freeport seam water. Twenty of our 44 sites had water quality information in 1980, which served as a midpoint to assess the slope of the decline in acidity and metal concentrations. Five of 20 sites (25%) showed an apparent exponential rate of decline in acidity and iron, while 10 of 20 sites (50%) showed a more linear decline. Drainage from five Upper Freeport sites increased in acidity and iron. While it is clear that surface mines and below-drainage underground mines improve in discharge quality relatively rapidly (20-40 years), above-drainage underground mines are not as easily predicted. In total, the drainage from 34 out of 44 (77%) above-drainage underground mines showed significant improvement in acidity over time, some exponentially and some linearly. Ten discharges showed no improvement and three of these got much worse.     

Water quality changes of a closed underground coal mine in Korea

The objective of this study was to assess the changes in mine water quality as an underground mine flooded from July 2005 to October 2008. The effect of air injection with a blower into the water was used to evaluate the potential to convert ferrous to ferric iron and to provide in situ treatment and precipitation. Mine flooding averaged 31 cm/day with a linear shape until November 2007, when it flattened out due to outflow. During flooding, mine water pH remained around 6, but Eh shifted from 200 to −150 mV. After the mine water level stabilized, contents of elements such as Fe and SO₄ tended to decrease as time passed. Air was injected by diffusers (150 L/min/each) at three different depths of 2, 3, and 5 m below the water level in the shaft. Dissolved oxygen eventually increased to 4 or 5 mg/L depending on the depth of the diffusers. Aeration caused conversion of ferrous iron to ferric iron and about 30 mg/l of iron was removed from the mine water. Therefore, air injection shows potential as a semi-active treatment or part of conventional treatment to precipitate iron in the mine pool.